Temperature Changes in Oral All-Ceramic Materials with Different Optical Properties under Er:YAG Laser Irradiation

This in vitro study is aimed at assessing the oral all-ceramic materials energy transmission and temperature changes after Er:YAG laser irradiation of monolithic zirconia all-ceramic materials with varying optical properties.

Two monolithic zirconia materials, Zenostar T and X-CERA TT (monolithic Zirconia), were studied. Specimens were divided into four groups, with a thickness of 1.0, 1.5, 2.0, and 2.5 mm, respectively. The chemical elemental composition of the two materials was determined using X-ray spectroscopy and Fourier transform infrared spectroscopy. The light transmittance of specimens with different thicknesses was measured using a spectrophotometer at three wavelength ranges: 200-380, 380-780, and 780-2500 nm. Irradiation with Er:YAG laser was performed, and the resultant temperature changes were measured using a thermocouple thermometer.

Compositional analysis indicated that Si content in X-CERA TT was higher than that in Zenostar T. The light transmittance of both materials decreased as specimen thickness increased. Er:YAG laser irradiation led to temperature increase at both Zenostar T (26.4°C-81.7°C) and X-CERA TT (23.9°C-53.5°C) specimens. Both optical transmittance and temperature changes after Er:YAG laser irradiation were consistent with exponential distribution against different thickness levels.

Er:YAG laser penetration energy and resultant temperature changes were mainly determined by the thickness and composition of the examined monolithic zirconia materials.